This company-wide fall crossover was centered on the Avengers and Fantastic Four after three consecutive fall crossovers were built around the X-Men and related mutant teams. Promotional materials teased the idea of a wide array of super-villains facing heroes they had never met (or at least were villains that weren't part of the heroes' regular gallery).
To assist the master villains, Loki engineers a jailbreak at the Vault. The lesser villains are then directed against heroes (mainly the Avengers and Spider-Man) who have never fought them before, the theory being that the unfamiliarity will act in the villains' favor.
While they did manage to give many of the heroes unusual fits, the plan eventually fails as the master villains fail to cooperate and bicker with each other. An example of this is where Magneto (who is a mutant and a Jewish Holocaust survivor) attacks Red Skull (whose Nazi beliefs in Marvel continuity include a prejudice against mutants) and imprisoning him in a buried crypt. The supervillain pawns are defeated by the heroes. A frustrated Loki reveals himself and imprisons the Kingpin, Mandarin and Wizard, while Doctor Doom is revealed to have been using a Doombot (Magneto is not present). The Avengers track the group and defeat the villains, with Thor forcing Loki to flee back to their native home of Asgard.